Satellites in low orbit, termed non-synchronous, have only limited volume available for the installation of antenna equipment. When the mission demands both high pointing agility and emitting, receiving and bipolarizing functions of the antenna, the volume allocated in terms of height for the installation of the antenna is often critical.
The known solutions for antennas with pointing agility do not simultaneously allow for pointing kinematics along with a bipolarizing function and an emitting and receiving function within a constrained volume.
Notably known is the design of a reflector antenna comprising a centred fixed source, in which the reflector possesses rotational symmetry and comprises a pointing mechanism that rotatively actuates it along two axes, i.e. azimuth and elevation. Pointing agility is obtained by virtue of the reflector's movement. However, the rotational symmetry of the reflector does not allow the gain of the antenna to be maximized at the limit of the coverage, nor control of the cross-polarization performance over a wide scanning field. Additionally, it is difficult to minimize the height of the antenna due to the position of the source, which is generally a significant distance away from the reflector and the length of the waveguide for reaching the source is considerable. Furthermore, this antenna solution does not allow operation at high angles of elevation.
Also known is the design of an antenna with dual reflectors comprising a source positioned in front of the secondary reflector, in which pointing agility of the antenna is obtained on an azimuthal axis by virtue of the movement of the assembly of the two reflectors and the source. The pointing agility of the antenna on an elevation axis is obtained by virtue of the movement of the assembly of the two reflectors with respect to the source, which remains fixed. The disadvantages are that this antenna solution does not allow a bipolarizing function and furthermore, the volume required for the installation of the antenna kinematics is considerable.
Also known is the design of an antenna comprising a centred reflector, in which pointing agility is obtained by an assembly of three linear actuators associated with articulated arms. The bipolarization radiofrequency junction is ensured by two coaxial cables. The disadvantages are that this solution presents considerable bulk, mass and cost. Furthermore, the radiofrequency links made by means of flexible coaxial cables present problems regarding lifespan.